OAKLAND -- On a perfectly gorgeous Wednesday in the East Bay, there were as many unoccupied green seats in the vast Coliseum as those containing bodies. This was normal for the A's, who played with their characteristic edge in dismissing the Angels, 9-8, to take a showdown series in front of 21,150.

If baseball fans in the discerning Bay Area are having a hard time believing the A's are for real, it's only because they're not facing them on a field graced by champions and legends in earlier eras.

"This franchise has a history of exciting teams and some raucous times," Angels second baseman Howie Kendrick was saying as his disappointed team headed home at last following a three-stop trip. "You go all the way back, it's been that way. Guys who played here liked to have a good time.

"You can kind of feel it with this team. Those guys are playing with a lot of energy, loose and free. They're confident and they're exciting. They want to show how good they are."

There are no Reggie Jacksons, Rickey Hendersons or Bash Brothers in this outfit. But that might be what's driving a team with a chip on its collective shoulder, determined to show the world it belongs on the big stage.

The A's own season series leads against the Angels (7-5), Yankees (4-3) and Red Sox (6-1) and are 6-6 against the Rangers. Only the Mariners, Indians, D-backs and Giants have series edges over Oakland.

"Never a doubt in my mind," right fielder Josh Reddick said when asked about the A's ability to compete with the big-market titans. "It's always about reaching the postseason. There's a lot of baseball left, though. We're not focusing on that yet."

In a virtual home run derby on Wednesday, seven were launched, five by the Angels. But Oakland prevailed, driven, according to closer Ryan Cook, by an all-for-one, one-for-all attitude.

"The one thing I can say about this team is every person in this clubhouse believes in one another," Cook said following a harrowing escape in the ninth. "That weighs heavily. We're not getting hits or outs for ourselves - we're getting them for everybody.

"It's an extremely selfless team. It's chemistry. Top to bottom, it comes from a belief we have in each other. There are days when [the offense] is struggling, and we're going to keep them to one less run. And there are days when they're raking, and we're going to do our part to keep it under control."

With disciplined, timely hitting, the A's had Zack Greinke out of Wednesday's game after five innings. This left it to a strapped and sapped bullpen, and it wasn't pretty.

LaTroy Hawkins, the Angels' most reliable reliever of late, was victimized by five runs in the sixth while getting two outs. Chris Carter's two-run homer and Yoenis Cespedes' two-run single were the big blows.

The A's held on -- barely.

"Although it wasn't perfect -- in terms of perfectness -- it was fine with me," Cook said. His 12th save presented fellow reliever Pat Neshek (1-0) with the win.

In his second big league start, Dan Straily couldn't make it through the fifth, yielding five earned runs on eight hits. Kendrys Morales went deep twice for the second time on a 4-6 road trip, and Chris Iannetta and Torii Hunter unloaded solo homers.

Mark Trumbo would join the homer party with No. 29, matching his rookie output, in the seventh against Grant Balfour.

Singles by Albert Pujols and Morales left Cook in trouble in the ninth, protecting a three-run lead. Kendrick's two-out, two-run single had the fans squirming in those green seats.

Kendrick stole second, but Erick Aybar -- 7-for-12 in the series after stepping in with two singles earlier in the day -- grounded out. The A's exhaled.

"It was a bit of a heavyweight fight there at the end," said A's manager Bob Melvin, who has infused his players with a trust and sense of freedoms enabling them to excel beyond all expectations.

The A's are 60-51 with 51 games left. Since June 2, their 38-21 record is the best in the Majors. They are a playoff team today, and you'd have to pay close attention to details -- as they clearly do -- to understand why.

They don't score a lot of runs, but they give up fewer with a resourceful pitching staff backed by a solid defense. The outfield, with Coco Crisp flying around center and Cespedes and Reddick taking guns to the corners, is first-rate.

"If I had to use one word to describe us, I'd say overwhelming," said Reddick, an emerging star acquired from Boston over the winter. "I don't want to say scrappy -- that's been used too much -- or surprising. I think we're overwhelming, to everybody in the league who thought we weren't going to be any good."

The Angels, at 59-53, are seven games behind the Rangers in the American League West. The A's trail Texas by 5 1/2.

Unless they go on a torrid run and Texas loses its grip, the Angels will need to enter the postseason through a Wild Card door that can slam shut very quickly. As in one and done.

The race for those two Wild Cards could turn out to be the most fascinating of all, given that half the league -- seven clubs -- can make a realistic claim to contention.

"Seems like it's been a long trip," said Trumbo, who showed signs of busting out of a slump with a line-drive single preceding his towering homer to left center. "It should be good for us to get back home and play in front of our fans. It's time for us to start playing to our capabilities."

A 10-game homestand starts for the Angels on Friday night against the Mariners, who will be followed into Angel Stadium by the Indians and Rays.

The A's open a three-game series against the White Sox in Chicago on Friday, then it's on to Kansas City for three.

Even if the rest of the world finds them unbelievable, the A's truly believe in the A's.

Lyle Spencer is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.